maybe we should have rented a new one ??

That may be risky too.  We have over 317k on our Duramax and it had more mechanical issues in the first 37k than is has had in the last 280k.  I would trust it about anywhere so long as the code reader is with to clear a code to get it out of limp mode (the joys of emissions).  FWIW there are just over 317k on the front wheel bearings and no funny tire wear so I will keep running them.